package com.itheima.pattern.singleton2.demo4;

public class Singleton {
    
    private Singleton () {}
    
    private static volatile Singleton instance;
    
    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null){
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
}
